I haven't taken the covers off in a while but my vague recollection is that the bare levers don't look terrible -
more of an old school textured look rather than sleek and shiny like, for example, Dura-Ace 7900 downtube levers. I prefer the feel and extra scuff protection of the covers, but unless Shimano has changed the 9 speed levers in the last ~10 years I think they'd look fine naked. I have no idea what the 10 and 11 speeders (if any) look like underneath.